This invention generally relates to wireless hybrid time division multiple access/code division multiple access communication systems. More particularly, the present invention relates to measuring interference signal code power in such systems.
A measurement commonly used in hybrid time division multiple access (TDMA)/code division multiple access (CDMA), such as time division duplex (TDD)/CDMA or time division synchronous code division multiple access (TD-SCDMA) wireless communication systems is interference signal code power (ISCP). ISCP is a measure of the interference in a particular time slot. This measurement has many applications, such as for time slot and channel assignments for the system's users.
FIG. 1 is a simplified diagram of an ISCP measuring device of a radio frequency (RF) receiver 30. To allow the automatic gain control (AGC) 12 to settle, the AGC 12 is turned on slightly prior to the midamble portion of a communication burst. This time period is typically 50 chips prior to the midamble. The midamble is the portion of a communication burst containing known training sequences.
The midamble is received by an antenna 10 or antenna array. The AGC 12 normalizes the power level of the received RF signals. A sampling device 14 samples the received signals at the chip rate or a multiple of the chip rate. A midamble processing device 16 processes the received signals with a code associated with the receiver's midamble code(s). Using information from the midamble processing and the control value of the AGC 12 (representing the AGC gain), an ISCP calculation device 18 determines the ISCP measurement.
A drawback to measuring the ISCP in this manner is the processing power required. The midamble processing and the ISCP calculation require considerable processing power and receiver on time. By reducing the processing power and receiver on time, power usage for a user equipment is reduced and, accordingly, battery power consumption is reduced. The reduced battery power consumption extends the battery life of the user equipment.
Accordingly, it is desirable to have other approaches to calculating ISCP.